The advantages of being able to calculate the location of a movable device are enormous, but measuring the location of a movable device can be difficult. And many applications need to track a movable device by repeatedly measuring the location of the movable device. Some known devices have problems. Devices based on gyroscopes are prone to accumulating errors and need to be reset periodically. Devices based on measuring radio waves may suffer from interference from many other devices that generate radio waves. Devices based on videoing the real person or lights attached to the real person (or object) and then calculating the person's (or object's) location by computational methods requires expensive hardware to implement. Additionally, it may be that the movable device is wireless so that the power source must be contained in the movable device.
Therefore, there is a need in the art for reliably calculating the position of a movable device that does not rely on radio waves or gyroscopes.